THE EFFECT OF TRAILING-EDGE GEOMETRY ON CAVITY FLOW OSCILLATION DRIVEN BY A SUPERSONIC SHEAR-LAYER

A computational analysis is performed of self-sustained oscillatory fl ow over a cavity driven by a shear layer at Mach 1.5. The unsteady flo w is studied through solutions of the Reynolds-averaged Navier-Stokes equations with turbulence modelled by a two-equation k-omega model. Th e trailing edge (face) of a baseline rectangular cavity is modified us ing wedge and ramp shapes to investigate means for the suppression and attenuation of the self-sustained oscillation. Through modification o f the shear layer impingement, both wedge and ramp are effective in re ducing the level of oscillation. The time-averaged pressure (form) dra g coefficient of the cavity is also reduced significantly. The main ca use of the drag reduction is the elimination or reduction of the high pressure area near the downstream corner of the cavity due to the pres ence of a vortex. Two types of unsteady flow exist when a curved ramp is employed: 'regular' and 'random'. The use of a h = 0.6D ramp genera tes a random type pressure fluctuation with lower rms pressure compare d with the h = 0.2D and 0.4D ramps.